martin



T. G. MARTIN.

AUTOMATIC OR SEMLAUTOMATIL TELEPHONE SYSTEM.

APPLICATION FILED FEEL-19.1949. RENEWED OCT. 2a, 1915.

1 08,740. Patented July 1, 1919.

HTTO/PA. :zrr's T. G. MARTIN.

AUTOMATIC 0R smmummnc TELEPHONE svsnm.

APFLICAYION FILED FEB. X9. i9i4. RENEWED OCT-28,1918, 1,308,740, Patented July 1, 1919.

3 SHEETS-SHEET 2.

Q fllfllllllilll-II T. G. MARTIN.

AUTOMATJC 0R SEMLAUTGMAHC TELEPHONE SYSTEM. AFFLHZATEON man FEB. 19, 19:4. RENEWED (M23128. 1918.

1 308,740. Patented July 1, 1919.

3 SHEETS-SHEET 3- UNITED STATES PATENT OFFICE.

TALBOT G. MARTIN, F CHICAGO, ILLINOIS, ASSIGNOR T0 AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC 0B SEMI-AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented'July 1, 1919.

Application filed February 19, 1914, Serial No. 819,678. Renewed October 28, 1918. Serial No. 260,063.

To all whom it may concern:

Be it known that I, TALBOT G. MARTIN, a citizen of the United States of America, and resident of Chicago, Cook county, Illib nois, have'invented certain new and useful improvements in Automatic or Semi-Automatic Telephone Systems, of which the following is a specification.

My invention relates to improvements in automatic or semi-automatic telephone sys tems and has for its object several features of improvement whereby the eflicicncy of operation of these systems is increased.

Among the objects of my invention is the 16 improved manner of giving a busy signal to an operator in a semi-automatic system when an attemp't'is made to establish connection with a busy line. This improvement relates to the type of busy signal 20 known as the flash bllS}"--thall is, a busy signal which is given by the flashing of a supervisory lamp at the operators position. The feature of my invention is an improved manner of operating this type of signal by 26 intermittent reversals of current which are controlled by the busy signaling machine. A further feature of m invention relates to an improved manner of disconnecting the ringing current from the called line either during the ringing or non-ringing period. A further feature of m invention relates to improved means for se ecting order wires which extend between operators ositions. These and other objects of my invention 36 will be more readily understood by reference to the accompanying drawings, in which Il have illustrated in invention in connection with auton'iatic switches and cord circuits of well-known ty es.

In the drawings Fi ures 1, 2 and 3 taken together show aconip ete circuit connection established between a calling manuahsubstation T and a called automatic substation A. Fig. 1 shows the manual substation -T, an individual or line switch C, an answerin jack equipment F and an A-operators cord S, together with the automatic order wire sclectmg apparatus E. f Fig. 2 shows a B-operators equipment 1. Fig. 3 shows an automatic connector switch H, an individual or line switch C and an automatic substation A.

The manual substation T (Fig. l) is an ordinary common battery manual telephone 66 comprising theusual receiver 2, transmib British patent to R. 7. James No. 26,301

of 1906, being, however, of the particular type disclosed in British atent to T. G.

Martin No. 1419 of 1910, a ove referred to.

The function of the master switch, as is well known, is to maintain the plungers of all the idle line switches in position to engi g e the terminals of an idle trunk line.

he answering jack equipment shown a} F (Fig; 1) comprises the usual line relay 21 cut-ofl' relay 22, lamp.23 and jack 24.

The cord circuit s (Fig. 1 is a wellknown type of cord circuit comprising the usual answering and calling plugs P and P, respective] inductively connected together through tiie condensers 25 and 26. The usual supervisory lamps 27 and 28 are shown as controlled by the relays 29 and 30, respectively. By means of the key K the A- operator can connect her talking set 0 with the cord circuit S and by means of the key K the calling plug may be disconnected from the answering plug and ringing current from the ringing current generator 31 projected upon said calling plug.

Associated with the operators head set there is a switch E for the pur ose of selecting an idle order wire exten ing to the B-operator. The switch shown at E (Fig. 1) is the same in general as the subscribers individual switch C, being somewhat simplified, however, in that it is provided with no line or cut-off relay armatures. This switch belongs to a group which is controlled by a master switch (not shown) similar to the master switch D (Fig. 1).

The B-operators equipment shown in Fig. consists of the usual 0 erators talking set L and the cord circuit This cord circnit comprises a supervisory lamp 182 controlled by a relay 181 connected to the third ter 3, ringer 4 and condenser 5. At the centrunk conductor 106. An impedance 1.31 is bridged across the cord on the calling sale of the condensers in conductors 14R and 1-H), which bridge is controlled by the polarized relay 32 bridged across the called side of said condensers. This last-mentioned bridge is in turn ontrolled by a third relay 121. A calling device key K is likewise provided the purpose ofwhich is to connect a calling device indicated by the springs 11.2 with the trunk line, through the medium of which calling device the operator may interrupt the bridge across the trunk line w desired number of times for each of the digits of the number of the called subscriln-r to control the automatic switches to set up the proper connection. This calling device may be of any desired type, such. for instance. as that shown in British patent to S. (1. S. Dicker No. 29.654 of 1910.

The onnector switch 11 (Fig. 3) is of the same general type of connector switch as disclosed in l'nited States Patent No. 815.17, granted March 1?). 1111111, to Keith. Erickson and Erickson. the circuits. however, being modified to adapt the switch to operate in a system in which the central of fice apparatus is controlled by impulses dc livcred over the two sides of the line in seri s. and being further modified o oper ate in accordance with the features of my invention. Among other details. the coir ncctor H comprises a bank of contacts ar' ranged in horizontal rows or levels, which contacts are adapted to be engaged by a set of wipers 33. 31 and 35 carried upon a shaft (not shown) which has a vertical movement controlled by the vertical magnet 36 and a rotary movement controlled by the rotary magnet 37. The operations of the various parts of the switch are controlled through the medium of a double wound line relay 43 said relay being connected with the line through the c1n'rent-rcversing springs of a so-called back-bridge relay 44. through the windings of which latter relay the called line. is provided with talking current. The line. relay -13 controls the circuit for the slow acting relay 49. which in turn controls a eir cuit for a second slow acting relay 5O adapts ed to be connected in series with the operating magnets 36 and 37. This relay 50 controls the circuit of the private magnet 42, which magnet controls the usual side switch comprising the wipers 38, 39, 40 and 41. The release of the switch is controlled by means of the release magnet 46. the circuit of which is controlled by the off-normal springs 47', which s rings are adapted to be closed only when tiie switch shaft has been raised one or more steps from the lowermost position. A second pair of cit-normal springs 48 is likewise provided, through which springs a locking circuit forthe relay 153 is completed. Connected in series h is relay 153 is a relay 151$,the circuit of which is controlled by the slow acting relay 50 in a nnmner to be hereinafter more fully described. The ringing current is sup plied to the called line from the ringing generator It by means of the ringing relay iii t'OllllOl'lltl in series with an interrupter 1:16. A ringing cut-oil relay 1i is provided for opening the ircuit of the ringing relay 1; to thereby cut off the ringing current from the called line. 4onnected in series with the ringing generator R is a relay 137 which only responds to direct current and which operatcs'in a manner hereinafter described to cut oti the rii'lging current from the line.

The 'circuit connections and the manner of operation of these various relays and mag nets will be more fully pointed out in connection with the description of the operation of the connector.

Associated with the connector ll is a busy signaling machine Q which consists of an induction coil or transformer, the primary winding of which is included in a local circuit with battery and two interrupter-s. one of high l'rcipiency and one of low frequency. This induction coil, as shown. comprises the primary windings 1138 and 1139 and the secondary windings 171 and 172. The primary windings are connected in series through an interrupter controlled by the pendulum 167 secured to the armature 170 operated by the coils 168 and ltiti'and this interrupter is connected in series with a second interrupter controlled by the pendulum 166 secured to the armature 1111 eontrolled by a pair of coils 1G3 and 164: This second interrupter is made slower than the first interrupter. as the pendulum of this interrupter is weighted. Through the me dium of these interrupters an intermittent interrupted current is supplied to the primary winding which induces an intermittent alternatin; current in the secondary wind ing, whereby when said winding is connected with the subscribefs line an intermittent buzzing sound is heard in the receiver. The armature 161 also controls a pair of contact springs 179 which cooperate in a manner to be hereinafter described to cause a supervisory lamp 28 at the operators position to be flashed to thus give the operator a busy signal. It will thus be seen that when the busy machine is connected to the line, the calling subscriber will hear the busy tone in the receiver and in addition thereto the A-operator will be informed that the called line is busy by the flashing of the supervisory lamp.

The subseribei"s individual switch C (Fig. 3) is similar in all respects to the switch shown at C. The automatic substation A (Fig. 3) comprises the usual receiver 2, transmitter 3, ringer 4' and con- 61611501 5'. Being an automatic substation it is also provided with a suitable call-sending mechanism for, controlling the auto matlc switches, which mechanism is represented diagrammatically by a pair of 1mpulse springs 51 and 52 and an impulse Wheel 53, which latter may be controlled by a dial provided with finger holes in such a way that the-impulse springs may he momentarily separated a number of times corresponding to the respective digits of the number of the called subscriber.

For the purpose of supplying battery current for operating the apparatus and for talking purposes, there are shown the batteries B and B, each having one terminal grounded at G and G, respectively.

A general description of the apparatus having been given, it will now be explained how a connection can he established between the line of substation T and the line of a called substation A. The number of the called line will be assumed to be 22. Since the apparatus disclosed herein is in general well known in the art, and as it is described 1 in the publications herein referred to, its operation will be explained in a more or less general manner. a

When the subscriber at substation T removes his receiver 2 preliminary to making a call, an energizing circuit is closed through the line winding 10 of the line switch (1. This circuit extends from ground G through "the springs 54 and 55, conductor 56, substation T, conductor 57, springs 58 and 59 and the line winding 10 to battery B. The armature 60, upon beingoperated, closes a circuit from ground G through the springs 54 and 61, pull-in winding 8, auxiliary winding lland the springs 62 to battery B. The pull-in winding 8, upon energizing, attracts both the armature 12 and the plunger arm 6. The plunger arm, upon being attracted.

forces the plunger which is attached to the end thereof into the bank of trunk terminals to which it has access, forcing the springs 13, 14, 15 and 16 into engagement with the springs 17, 18, 19 and 20, respectively. The engagement of the springs 13 r and 16 with the springs 17 and 20, respectively, closes a circuit through the line relay 21, shown at, F. This circuit extends from ground Gr through the lower winding of the relay 21, springs 63, springs 20 and 16 conductorfio, substation T, conductor 57, springs 13 and 17, springs 64 and the upper winding of the relay 21 to battery B. The relay 21, upon energizing, closes a circuit from ground G through the springs 65 and the springs ISjand 14 to the point 66, thence one branch extends over the conductor 67 to the bush of all multiple jacks associated with the line of the substation T. This guarding potential prevents connection being made with the line of substation "I while said substation is calling. Another branch extends from the point 66 through the hold ing winding 9 of the line switch (7 to battery B. This circuit through the holding wind ing 9 is closed before the armature (it) falls back after the circuit through the line winding 10 is broken by the attraction of the armature 12. The armature (it) does not fall back immediately upon the pulling up of the armature 12, due to the fact that simul taneous with the attraction of the armature 1:2 is the pulling up of the plunger arm 6, which.short-circuits the auxiliary winding 11 by closing the springs (38. his shortcircuiting of the winding 11 tends to retard the deinergization ot' the core, and thus the armature 60 is held in an operated position until enough time has elapsed for the circuit through the winding 9 to be closed, whereby the plunger arm 6 is held in an operated position.

The relay 21, upon energizing, also closes a circuit from ground G through the springs 69 and lamp 23 to battery B. Upon receiving the signal of the lamp 23 the operator inserts the plug P into the jack 24, whereby the calling subscribcrs connection is extended to the cord S and a'circuit is closed through the cut-oft relay 22 of the trunk and the calling supervisory relay 2!) of the cord. The circuit of the relay 22 extends from ground (i through the relay 22, bush of the jack 24, sleeve of the plug P and the resistances 70 and 71 to battery B. A branch of the above circuit extends from the sleeve of the plug P through the lamp 127 and the springs 72 and 73 to battery B. The relay 22, upon energizing, disconnects the relay 21 from the trunk, and because its springs are adjusted so that the springs 74- make contact before the springs 63 and (H break contact, a new holding circuit is es tablished from ground G for the winding 9 of the line switch C before ground G is removed. The deenergization of the relay 21 extinguishes the lamp 23. The relay 29 energizes over the heavy conductors shown and in its energized position maintains the circuit of the lamp 27 open and short-circuits the resistance 71,

The operator then throws the listening key K to connect the talking set with the calling-line and upon learning that a connection is desired with one of the subscribers who is called automatically by the B-opcr ator. the operator at the cord S depresses her order wire key 75. The closure of springs 76 and the spring 77 forms a circuit from ground G through the left-hand winding of the-relay 78, s rings 77, impedance coil 79, springs 76 ant the right-hand winding of the relay 78 to battery B. The springs of the relay 78 are so adjusted that the springs 80 make contact before the springs 81 make contact. Upon the energization of the relay 78 a circuit may be traced from ground (i through the springs till, springs 82. pull-down winding 53, s irings Bland 85 and through the springs on the master switch (not shown) to battery B. An instunt later a circuit would he formed from ground (i through the springs 81, springs 86 and the relay 87 to battery ll. However, the time elapsing between the formation of the whore-traced circuits is sullieicnt for the winding 33 to attract the plunger arm 88 and force the plunger into the bani: of con tacts till to 95, inclusive. A. the same time the springs PM are separated. than opening the second circuit above traced. The spring 95 up n melting ontact with the spring 8% and causing same to separate from the spring 85. places the high resistance wind in 96 in series with the winding 83, thus reducing the current consumed. Upon the plunger forcing the springs 90 and 92 into engagement. with the springs. 93 and 95, respectively the A-operator is connected [lirectly with the B'operator s talking set L (Fig. 2).

Should all the trunks be busy battery would he removed from the pull-in Winding in the usual well-hnown manner. hen an operator presses the order wire key 75, therefore, the circuit through the pull-in winding 83 will not be formed, due to the absence of battery on the Winding 83. An instant later the second circuit through the relay 87 will he closed and the relay 8? will become energized and in so doing open the said first circuit at a. second, point at the springs 82. Also, the busy tone will he given the. operator through the springs 97 and the conductor 97 leading to a busy machine. When one or more of the trunks heroine idle and the hattery is returned to the pull-in windings. the winding 83 will not he energized on net ount of the open cir cuit at the Springs 82. Thus it. will be Seen that should an opriater at the husy tone upon pressing an [)il1i key. it will he necessary that si -+hould release the key and thus dei nerg iirit". relay T8 and 4M1 ticthen again press the h. a rorc bile. can secure connection with l lfilL:

It, will be seen that in long as. the ll opeu ator has her talking-net mnnected at her position, the current flowing through her transmitter will energize the relay 98, which in turn keeps the two sides of the trunk open at the springs 99. In case a Boperator wishes to leave her position, the simple operation of disconnecting her talking set from the trunk lending to said position autou'iati cally renders the trunk husy over circuit from ground ll" through the left-lewd wind ing of the relay 100, trunk conductor it'll, springs 99. trunk conductor 102 and the right-hand winding of the riiay 100 to huttery B. The relay 190, upon energizing over this circuit, places ground from ground Gr upon the master switch hank contact associated with its trunks, in this way making the trunk husy. At the same time the relay 100 closes the springs 103: said springs being two of a chain which are looped through the. relay, which corresponds to the relay 100, in each trunk, and should all the trunks become busy, a circuit is completed through the relay lO-l. said relay operatin to stop the master switch (not shown) am remove battery from the pull-down coils.

l pon receiving an order for a connection over the order wire selected in the manner explained above. the B-operator assigns an idle trunk line to the A-operator, whereupon the A-operator releases the key 75 and inserts the plug 1" into the jack 105 of the trunk assigned. Upon the insertion of this plug, a circuit is closed from ground G through the relay 181'. conductor 106, hush of the jack 105, sleeve of the plug P, lam 28 and the springs 107 and 108 to battery A. branch of the above-traced circuit extends from the sleeve of the plug I" through the resistance coils 109 and 110 to battery B. The relay 1S1, upon energizing. closes the circuit of the lamp 182. and the lamp 28 lights over the above-traced circuit to inform the A-operator that the called party has not yet answered. The B-operator new places the plug l into the jack 111 of :1

trunk line leading to the connector H and the key K is operated to connect the calling device 112 with the trunk. A circuit is thereby completed extending from ground G" throughthe lower winding of the relay -43, springs 113 and 114, conductor 115, ring of the jack ll 1, ring of the plug 1", springs 116 and 1.17, the springs of the calling device 112, s irings 118 and 119, tip of the plug P tip o the inch 111, conductor 120, springs 121 and 122 and the upper winding of the relay -13 to hatter-y B. The relay 43, u on energizing", closes a circuit through the s ow acting relay 49. which relay, upon energizing, prepares the circuit of the vertical magnet 36 and opens the circuit; of the release magnet 46. Vl lien the key K is operated, another circuit may be traced from ground (1 through the springs 123 and the re,- la ii?! to battery B. The relay 124, upon energizing, forms a. locking circuit for itself from ground G through the springs .195, spring 126 and the relay 124- to battery B.

The relay 124 also prepares the circuit for sequently each time the latter relay delinerg zes. an impulse is transmitted over the circuit extending from ground G through K the springs 12S and 129, springs 130 and 131,

relay 50, vertical magnet 36 and the side switch wiper 38 (in first position) to battery B. The vertical magnet receives two impulses over this circuit and operates to raise the switch shag: and wipers two steps to a position oppo'f e the second row or level of bank contacts, and at the same time the shaftcontrolled contacts 47 and 48 are closed. The .slow acting relay 50 is maintained in its energized position continuously while impulses are being transmitted to' the vertical magnet through it, and in its energized position closes a circuit from grpund 6"" through the springs and 133 and the plliViliit magnet 42 to battery B. This circuit is broken when the relay 5O dei nergizes after the last impulse has been delivered to l the vertical magnet. The breaking of said circuit causes the private magnet 42 to de' energize, thus permitting the side switch to pass to second position. In passing from first to second position the side switch wiper 33 transfers the battery connection from the vertical magnet 315 to the rotary magnet 37.

The B-opcrator now operates her calling device for the last digit 2, in response to which the connector line relay operates to transmit two impulses through the rotary magnet 37, whereby the shaftwipers are rotated onto the contacts of the desired line. The circuit of the rotary magnet extends froih ground G through the springs 128 and 12%), springs 130' and 131, relay 50, springs 134, rotary magnet '37 and the side switch wiper 38 (in second position) to battery B. The relay 50 operates in response to the impulses for this digit in the same manner as for the previous digit to cause the private magnet 42 to advance the side switch to third position. By the engagement of the side switch wipers 39 and 40 with their third-position contact points, the line connectiorris completed with the called line. Upon the engagement of the side switch wiper 41 with its third-position contact point, a circuit is completed through the cut-elf winding of the line switch C. This circuit extends from ground G through the side switch wiper 41 in third position), private wiper 34, bank contact 134, and the ,rutoti winding 135 of the line switch G'to battery B. The cut-offwinding of the line switch (1, upon energizing, operates to disconnect the line relay from the called substation. The connection of ground G with the connector private bank contact associated with the called line'prevents the called line from being seized by some other connector switch. 7

By the engagement of the side switch wiper 38 with its third --positidn Contact point. the circuit of the ringing relay 45 is closed. This circuit extends from ground G" through the interrupter 136, springs 13?, ringer relay 45 and the side switch wiper 38 (in third position) to battery B. The ringing relay is energized intermittently due to the interrupter 136 and operates to disconnect the calling line from the called line and to bridge the ringing current generator R across the called line to signal the called subscriber. The signaling circuit extends from ground G through the springs 141 and 140, wiper 33, to and through the substation A, wiper 35, springs 138 and 139, relay 137, ringing current en- 80.

orator R and battery B to ground G. he condenser 5' at the substation A will not allow the direct current from battery B to pass over thiscircuit, and therelay 137 is adjusted not to respond to ringing current. Should the receiver at the-called substation be removed while the ringer relay 45 is in an operated position, a circuit for direct current is formed and this flow of direct currtnit'energizes the relay 137. The relay 137, upon energizing, closes a circuit which may be traced from ground G through the springs '48, springs 142, 'r elay 143 and the side switch wiper 38 (in third position) to battery B. The relay 143, upon energizing, opens the circuit of-the ringer relay 45 at the springs 137* and closes a locking circuit for itself through the springs 144. independent of the springs 142. The ringer relay 45 immediately deenergizes upon its circuit be- {on ing opened and the back-bridge relay 44 then supplies the called substation with talking current. .The back-bridge relay 44, upon energizing, reverses the current in the trunk with results hereinafter explained. Should the called subscriber remove his receiver while the ringer relay 45 is at normal, a circuit will immediately be closed through the back-bridge relay 44. Said relay, upon energizing, will close a circuit from ground y 2 through the springs 48, springs 145, rolay 143 and the side .switch Wiper 38 (in third position) to battery B. The relay 143, open energizing, opens the circuit of the ringer relay 45 at the springs 137 and 116 closes a locking circuit for itself through the springs 144 independent of the springs 145.'. After the B-operator has dialed the called, number she restores the-key K to normal, andas the key K. is adjusted to make contact with the contacts 146 and 147 before it breaks contact with the springs-118 and 117, the circuit of the connector line relay 43 is transferred from the calling device 112 to a circuit extending from the spring 119, com tact 146, polarized relay 32, springs 127, contact 147 to the spring 116 and back to the relay 43. The current flowing through the polarized relay 32 at this time is in such a direction that said relay does not close the 189,

('ontact of springs 1.70, Upon the rallell subscriber ramming his rerviver from the hook, the l):l!l{-l)l'lil f(. relay onorgimn aml operates to rcrcrar he rurronl in lilo li'llllii. This ruvurno Purren't [lowing through llnpolurized relay 32 mosses it to ho opoi'atiu-ly energized 21ml :1 'iri'uii' is losocl from ground U (Fig 1 through tho lower uinilii'ig of the. relay 3U, sprin' ol' koy K ring ol tho plug P and javk 105. conilurior l-tr springgo 150, impedance (.Ull 15L ronilnrtor iii]; tip of the jark 105 and the) plug P. spring of the key K and tho upprr winding of the relay S0 to ll-aitery B, Th0 roloy 30., upon rnvr izing i'ipuratoa to open the rirrnit of the lamp 1H and shunt the rooiniaaw 110. The uxtinguishing of the lamp 2%; notiiios; the A prrator than {hr railwl pair sworrdi The lamp 181! ut tho li-i llfii'ti Continue lighted so long; as the plug i" left in tho junk 1115 Upon tlu' ironli'ilvtion of the cruivcrsalion the calling Mlhiilllfil' by hanging up his receiver, opens the Circuit of the relay 29, whereby. when iaizl relay iloi nei'gizohr, tho supervisory lump :5? is lightwl. Thu railed subsrrilmu up n h. n 7 up his rea'uivt-r, opyna the circuit of the: hank-bridge relay. whureby ihe iiiiili'iili'rl g'fi relay ilvinrrgizos mnl in doing on rover-:7 :5 tho flow of rurront in the trunk hack to no] illiii ilirnrtion. Thus the armature of tho poiurizoei relay 112? *0- turns to normal and in so doing opona tho circuit of the relay 30, whereby, whoa saiil relay returns to normal the aupowiuory lninp is lighted. The Apporalorfi upon seeing both tho answering anti rolling mpor visory lamps lighted, knoww, that lilrli'iyllllill'w tion is roquirvil and llilUVL'h a plug P from the jack ii. 'lhusthe riruuit of the relay 2: is oponril 21ml, upon the ciui nrrgizw tion of said relay. inn hoielin; gmzuul Hr" is removed from, lilo winding U of tho lino switch C, whirl-Quinn! t lu winding J (lo energizes and allows tin plungvr arm l} and tho arinalnro 1'3 to rvtum in normal At the same time the operai, ;-r rvnn' q tho plug P from the 105 and in no doing; the circuit of the relay 181 in upunfiil. which in turn, upon (loi nurgizing, opuns tinlorlr ing circuit of tho relay 113i. The rula 112i nponcle norgizing, open-1 rho rim-oi: of tho line relay iii of tho manna-tor H. hi-z :io energization of the relay 181 also opens tho cirnuii of the lamp 1821 Thu llaiprratorg upon seeing tlu lamp 152 extinguished knows that a discount-rt is: iluoirml illlli rm moves the plug P? from tho Earth 11L The lino relay 4: upon del nergi/liug, open the circuit of the relay {2). whirl: in turn upon dei nergizing, clowns n rinui: from ground G through Liie spring; 12H :lliLl 121', spring 130 and 15:5, QIF-norinal springs ET and the release. magnet; in to battery B. The? rulease niagnvt upon vrwrgmng, IUIIHHLm tlnrutaining pawls from the shaft and its own circuit is opunuil at the springs &7 when the \hal't has rearhui its loin-5t position.

It ha \ing been explained how the comm/:- liions are estuhlishud and released, ill will now he; uxplained how a connection is prevented from bving made with v busy line, how a husy tone is PKUVlilLll for calling subscriber alul how tho railing nulmrvisory lump of tho Apparator in flashed to inform her that the number called is busy. [f the called inunlaw is busy, then: will be a guarding potential upon the connector private hank contact asnociatod with thatlino. just as previously uxplaiiumt The connector private wiper 3i, upon engaging this guardvd contort and he form the side switch wipers have passed to third position, completes; an energizing ciruuitthrough the relay 1525. This circuit extends from ground at the private bank contact through the private Wipol 31, side witch Wiper 41 (in second position Springs 155- and 155 rnlay 1.53, reiay 1.14;, springs 157 and 133 and the private magnet 12 to battery B. The relays 153 and 156 and the magnet l2 onurgizn in series. The relay 153, upon oru-rgizing, opens the rirr-uit of the rotary magnet at the springs Ill-l and also forms a lurking rim-nit for itself from ground (F hrough tliv oil-normal springs iii, springs i581 and 1113, relay 153, relay 15H, springs lLii' urnl Iii-l and the pi'iYalu magnet l2 to buttery B. The rolay 153, when enurgizuil, also torma a circuit extruding from llll, oonlluutor 115 through the springs 159, Bill? ,sn'ituh wipor ,5) {in second position) and tin itlllfilfillfill lull to tho roiulnrtor l20. This rim-nit is ilwignml to rwluco no con- (lillhll' iliarhargv \Yll l'll a'onlil ollwru'irm take plavr Lhrmigl Llu: willing silllllHlfll'lUH \vhun tho lnu'lc hriilgu relay oprru rs in a manner lJr-ririnal'trr l-xplainuil.

l lull-rring to tho hu v machine Q, when the armaluro it i in tho position shown. a, circuit may luw trio-r11 from ground (1 through llnuprinw lii. polululum Hi6, lliilgllll lull, magnet 16 i and tho resistance U 5 to hattury ll. llpou tliu magnate, 163 aml l vl lam-inning tili'lg'lzvil in llllls numuor. tho polarizull armaturu lfil ()[itl'zllifi to upon the rirz'uifi of tin magnets ll'iil zuul 164; m tho -piings 1 31!. alul a: a rv ult the arlnalnro liil :uul prnliuliun 161i i'll'i' givon an osrillator i' motion, the spinal of which iS iloponilrnt upon tho weight of the pendulum 1G6 and is profera-ilily quinslow. Each time the arumturo 161 occupies the position shown, so that tho pvniluluin llifi oomos in t the windin 161 as long as the springs 162 are in contact, except at a much higher rate of speed, the pendulum 167 being lighter than the pendulum 168 and therefore havin a higher rate of vibration. From the foregoing it will be seen that the current in the windings 168 and 169 is of an interrupted pulsating nature, and that accordingly an intcrmittent alternating current will be induced in the windings 171 and 172. The relay 156 of the connector being energized, this induced current will pass through the windings 172 and 171, condenser 173, lamp 174, resistance 175, springs 176 and 177 of the relay 156, side switch wiper (in sec ond position) to and through the calling substation and throughthe upper winding of the relay-13 to battery B, and thence back 172. This busy tone in the receiver will inform the callin subscriber that the called line is bus gain referring to the busy machine (5, it will be seen that at the time the armature 161 is in an operated position (at which time there is no induced current in the windings 171 and 172), a circuit maybe traced from round G at the connector through the le t-hand winding of the relay 44, springs 178, 177 and 176, resistance 175, lamp 174, springs 179 and the resistance 180 to battery B. The back-bridge relay 44, upon energizin over this circuit, operates to reverse the ow of current in the trunk, whereby the calling supervisory lamp 28 is extinguished, as previously explained. The relay 44 operating intermittently, due to the periodical engagement of the spnings 179, causes the lamp 28 to flash intermittently, whereby the-A-operator is informed that the calledtelephone is busy. Should the calling subscriber hang up his receiver, the A-operator would then take down the connection, as previously explained, but should the callingsubscriber remain on .the line, the A-operator would then communicate with him and inform him that the desired number was busy, whereupon the calling subscriber, would hang up and the 'Aopcrabor would release the connection as before explained.

It'will thus be seen that I have devised a very efficient system in which the operator is given the busy signal by -the flashing of a. supervisory lamp, which flashing is controll d by the reversal of current. Furthermor it willbeseen that I havedevlsed very cflicient means for disconnecting the ringing current from the called line as soon as the called subscriber answers, whether this is during the ringing interval or duringa pause between the ringing intervals. It will furthermore be seen that I have devlsed very eiiicient and improved means whereby the A-operator can select an idleorder wire extending to the B-operators pos1t1on, to-

gether witlrmeans for preventing this A- operator from operating her trunk-selecting switch when all the order Wiresin a group are busy.

:hile I have illustrated and described my invention in connection with automatic switches of a well-known type, it will, of course, be understood that I do not wish to be so linnted,*as my invention is adapted for use in connection with many other types of automatic switches. Furthermore, it will be understood that in larger exchanges the well-known form of selector switches can be employed in order to extend the connection from the operators board to the con ncctor switches. Many other changes and modifications will readily suggest themselves to those skilled in the art and come within the contemplated spirit; and scope of my in vention.

What I claim as my invention is 1. In a telephone system, a calling and zucalled subscribers line, means for extending a connection from the calling line to said called line. a visual signal, means for interiuittently reversing the current over the connection extending to the called line when the called line is busy, and means operated by said reversal of current for intermittently flashing said signal.

2. In a telephone system, a plurality of subscribers lines, means including an operators board for extending a connection from a' calling line to it called lin'c, asignal, a polarized relay at said operators board, means for reversing the current through said polarized rcla'y when an attempt'is made to. connect with a busy line to thereby operate said relay, and means controlled by the operation of said relay to cause the operation of said signal.

3. In a telephone system, a plurality of subscribers lines. means including an operators board for extending a connection from a calling line to a called line. a signal. a polarized relay at said operator's board. means for intermittently reversing the cur rent through said polarized relay when an attempt ismade to connect with a busy line to thereby intermittently operate said relay, and means controlled by the intermittent operation of said relay to cause the intermittent operation of said signal.

4'. In a telephone system. subscribers lines, an automatic connector switch for cstablishing connection with said lines. means including a trunk line for extending a connection to said switch. a visual signal. means for reversing the current over said. trunk line when said connector attempts to make connection with a busy line, and means 0011- trolled by said reversal of current to cause the operation of said signal.

5. In a telenhone system, subscribers lines, an automatic bonnector switch for establishing connection with saidlines, means including a trunk line for extending a coin nection to said switch, a visual signal, means for intermittently reversing the current over said trunk line when said connector attempts to make connection with a busy line. and means controlled by said intermittent reversal of current to cause the intermittent operation of said signal.

(5. In a telephone system. a plurality of subscribers lines. means including an operator's cord circuit and a trunk line extending therefrom for extending a connection to said connector, a polarized relay in said cord, a signal controlled thereby, means for reversing the current in said trunk when said connector attempts to make connection with a busy line, and means controlled by said reversal of current for operating said relay to thereby cause the operation of said signal.

7. In a telephone system, a plurality of sub a-ibers lines. an automatic connector switch for estahlis ling connection with said lilies, means illtfllltllllg a trunk line for ex lending a connection to said switch, a supervisory signal. a back-bridge relay in said connector, means for energizing said relay when said connector attempts to make con nection with a busy line, means controlled by the energization of said relay for reversing the current in said trunk, and means con trollcd by said reversal of current for causin; the operation of said signal.

8. In a telephone system, a plurality of subscribers lines, means including an operators cord circuit and a trunk line extending therefrom for extending a connection to said connector. a polarized relay in said cord, a signal controlled thereby, means for intermittently reversing the current in said trunk when said connector attempts to make connection with a busy line, and means controlled by said intermittent reversal of current for intermittently operating said relay to therebv cause the intermittent operation of said signal. i

I). In a telephone system, a plurality of subscribers lines, an automatic connector switch for establishing coi'inection with said lines, means including a trunk line for extending a connection to said switch, a super" visory signal, a back-bridge relay in said connector, means for intermittently ener' gizing said relay when said connector zit-- temps to make connection with a busy line. means controlled by the intermittent energization of said relay for intermittently reversing the current in said trunk, and means controlled by said intermittent reversal of current for causing the intermittent opera tion of said signal.

10. In a telephone system, a plurality of subscribers lines, an automatic connector switch for establishing a connecting with said lines, means including an operators cord circuit and a trunk circuit extending tlnn'et'rom for extending a connection to aid connector, a polarized relay in said cord circuit, a signal controlled thereby, a back li-ridgc relay in said connector, means for energizing said relay when said connector attempts to make connection with a busy line, means controlled by the energization of said back'bridge relay for reversing the current in said trunk, and means controlled by said reversal of current to cause the operation of said polarized relay to thereby cause the operation of said signal.

11. In a telephone system, a plurality of subscribers" lines, an automatic connector switch for establishing a connection with said lines, means including an operatofs cord circuit and a trunk circuit extending therefrom for extending a connection to said connector. a polarized relay in said cord cirrail, a signal controlled thereby, a baele bridge relay in said connector, means for intermittently energizing said relay when said connector attempts to make connection with a busy line, means controlled by the intermittent energization of said back bridge relay for reversing the current in said trunk and means controlled by said intermittem reversal of current to cause the intermittent operation of sa1d polarized relay to thereby cause the intermittent operation of said signal.

12. In a telephone system, a(.'alling and :1 called subscribers line, means for extend in a connection from the calling line to said called line, a visual signal, means for reversing the current over the connection extendinsg to the called line when the called line is busy, a busy signaling machine for transmitting a busy signaling current to the calling line, means controlled by said busy signaling, machine for intermittently interrupting said reversed current, and means operated by said intermittent reversal of current for interlnittently flashing said sig i nal.

13. In a telephone system, a calling and a called subscribers line means for extend ing a connection from the calling line to said called line, a visual signal, means for revet-sing the current over the connection extending to the called line when the called line is busy, a busy signaling machine for intt'a'mittently transmittim a busy signaling current to the calling line, means controlled by said busy signaling machine during, the interruptions in said busy signaling eurreiit for in'lcrmittently il'iterrupting said reversed current, and mean-z controlled by said intermittently revelsed current for flashing d signal.

14. In a telephone system, a plurality of subscrihers line. means including an operator s board for er tending a connection from a calling line to a called line, a signal .11

polarized relay at said o 'ierator s board, means tor reversing the current through said polarized rclay when an attempt is made to connect with a busy line to thereby operate said relay, a busy signaling machine for transmitting a busy signaling current to the calling line, means controlled by said busy signaling machine for intermittently interrupting said reversed current, means op rated by said intermittent rcwrsal of'currcnt for intermittently operatin; said relay, and means controlled by the operation of said relay for flashing said signal.

1.3. ln a telephone tcm. a plurality of subscribers lincs, means including an operators board for extending a connection from a calling line to a called line, a signal, a polarized relay at said opcratons board, means for reversing thc current through said polari'ied relay when an att mpt is made to connect with a busy line to thereby operate said relay, a busy signaling machine for intermittently transmitting a busy signaling current to the calling line, means con-trolled by said busy signaling machine during the interruptions of said busy signaling current for intermittently interrupting said reversed current, means operated by said intermittent reversal of current for intermittently operating said relay. and means controlled by the operation of said relay for flashing said signal.

In. In a telephone system, subscribers lincs. an automatic connector switch for establishing connection with said lines,

means including a trunk line for extending a conncction to said switch, a visual signal. means for reversing the current ovcr said trunk line when said connector attempts to make comiection with a busy line, a busy signaling machine for transmitting a busy signaling current to the calling line, means controlled by said busy signaling machine for intermittently interrupting said re- \crsctl current, and nicans operated by said intermittent reversal of current for intermillcnlly tlashing said signal.

1?. In a telephone system, subscribers lines. an automatic connector switch for establishing connection with said lines, means including a trunk line .t'or extending a connection to said switch, a visual signal, means for reversing the current over said trunk line when said connector attempts to makc connection with a busy line, a busy signaling machine for intermittently transmitting a busy signaling current to the calling lima int-ans colll rolled by said busy signaling machine during the interruptions in said busy signaling current for intermittently interrupting said reversed current. and means controlled by said intern.ittently rcwrsed current for flushing said signal.

In. In a telephone system, a, plurality of subscribers lines, means including an operators cord circuit and a trunk lino extending therefrom for extending a connection to said connector, a polarized relay in said cord, a signal controlled thereby, means for reversing the current in said trunk when said connector attempts to make connection with a busy line, a busy signaling machine for transinitting a busy signaling current to the calling line, means control ed by said busy signaling machine for intermittently interru ting said reversed current, means operated y said intermittent reversal of current fortintcrmiltcntly operating said relay, and means controlled by the operation of said relay for flashing said signal.

19. In a telephone system, a plurality of suhserilmrs lines, means including an operator's cord circuit and a trunk line extending therefrom for extending a connection to said connector, a polarized relay in said 00rd, a signal controlled thereby, means for reversing the current in said trunk when said connccior attempts to make connection with a busy line, a busy signaling machine for intcrmittcntly transmitting a busy signaling current to the calling line, means controlled by said busy signaling machine during the interruptions of said busy signaling current for iiitcrmittcntly interrupting said reversed current, means operated by said intermittent reversal of current for interlnittcntly operating said relay. and means controlled by the operation of said relay for flashing said sig- Int].

.30. In a telephone system, a plurality of subscribers lines, an automatic connector switch for establishing connection wi h said lines. means including a trunk line for extending :1 connection to said switch, a supervisory signal, a back-bridge relay in said connector, means for energizing said relay when said connector attem its to make. eonneclion with a busy line. means controlled by tho energization of said relay for reversing the current in said trunk, a lousy signaling machine for transmitting a busy signaling current to the calling line. means controlled by said busy signaling machine for int/en mittentl y interrupting said reversed current, and means operated by said intermittent reversal of current for intermittently flashing said signal.

21. In a telephone system. a plurality of subscribers lines, an automatic connector switch for establishing connection with said lines. means including a trunk line for ex lending a connection to said switch, a supervisory signal, a back-bridge relay in said connector, means for energizing said relay when said connector attempts to make connection with a busy line, means controlled by the energization of said relay for reversing the current in said trunk, a busy signaling machine for intermittently transmitting a busy signaling current to the calling lluc, means controlled by said busy signaling ma" chine during the interruptions in aid l'iusy signaling current for llllGl'lIllllLllll) inter rupting said reversed current, and mcans controlled by said .intcrmittcntl reversed current for flashing said signal.

In a telephone system, a plurality of subscribers lines, an automatic connector switch for establishing a connection with said lines, means: including an operators cord circuit and a trunk circuit extending therefrom for extending; a connection to said connector, a polarized rcla in said cord circuit, a signal controlled thereby, a baclc bridge relay in said connector, means for ca ergizing said relay when said connector at tempts to make connection with a busy line, means controlled by the cnergization of aid baclclqridge rcla for reversing the current in said trunk, a busy signaling machine tor transmitting a busy signaling current to tlucalling line, means controlled by said busy signaling machine for intermittently intcn rupting said reversed current, means opcrated by said intermittent rcvcrsal of current for intermittently opcrating said relay, and means controlled by the operation of said relay for flashing said signal.

23. in a telephone system. a plurality ol' subscribers lincs. an automati comm-toiswitch for establishing a connection with said lint means including an tu'u-rator cord circuit and a trunk circuit extending thcrcl'rom for extending a rounurtiou to said connector, a polarized relay in said cord cir cult, a signal controlled thereby. a backbridge, relay in said cimm-ctor, means tor en ergizing said relay when said couucctol' attempts to make connection with a busy line. means controlled by the cucrggization of said back-bridge relay for reversing the current in said trunk, a busy signaling machine for intermittently transmitting a busy signaling current to the calling line, means controlled by said busy signaling machine during the interruptions of said busy signaling current, for intermittently interrupting said reversed current, means opcratcd by said intermittent re\'crsal of current for intcrmittentlyopcrating said relay, and means controlled by the operation of said relay for flashing said Ignal.

34. In a tclcphonc ystem. an ;\opcratoi"s board. a li'tllltltll'til s board, a group o'l or? dcr \rircs extending bctuccn said boards, a selecting switch associated nith thc A oucrator's board. an operating magnet there for, and means for opening thc circuit of said operating magnet when all the order wires in said group are busy,

in a tclcphonc srstcun an i\ o 1eratois oard, a ll operal'ous board, a group of or dcr uircs extending lictnemr aid lioai sclcctii.1; su'ilch associated with tln ith id switch while all llurdcr Wircs arc l i i. in a tcltiliouc systcm, a calling line,

:1 called than a. ircuit f r t ll'tllttlllllf the law; said circuit baring a manual sccti n and an automatic suction, the manual section iniuuallr Ulltl'lllt'tl trunk circuits and touiatii' -c 'tiou liaiing' all :Lutoum it: i sircly l|ltl\1tlllt trunhing switch, a lniltcrr l'or supplying curr nt tol'lu'saidcirmitts. a bus]: test circuit tor the tiillt'il line, a tin-ft signal l'or aid manual s ction. u t signal control mean ssociated with aid cut n and under tlic combined control oi said ll' l irrult and said auto null ic -lsll 'll to reverse llic batter su ud to the saul manua si-cliun il ili i'allcd liuc is bu t tor s rnam aid ignal and to lil'l \eni tlnperation ol' aid: anal it tlnlino litll lltlr-}',

it in a tcl dnun iciu. a calling liuc, lin a Er-nil tor c nnecting the two. dill lll ltll lowing a manual scction and in ,Iul uiiedic :cctiou, tlumanual scc i manually o icratcd trunk cirand thc uuloumlir -c tion liariirg an automatic uonicssnctr moraldc trunking su te-b. a liatlcrr l'or supplying currcnt to the said ircuits, a bus tcsl circuit for thc izt i d liuiu a bu y signal l'or said manual section. busy signal control mcaus associated uilh said automatic snitch and under tlic combined control ol' said test circuit and said il ll llililllt' snitch to rctcrsc llu' iattcry supply to thc said manual scction it tlu call d liuc is busy l'or operating" said signal and to gircvcul the operation of said signal it thc liuc is not, busy. lucaus tor aulomati "all r omit ing ringing, curri-ut to said lluc la-n the linc is not busy and {or iut riuiltcnily interrupt lug said ringing current, and incau coiuu-ctcd in series with the sourciol said ruining currcut tor tllsconuc 'tiu; said ringing current l l llll the liluas soon as the allcd suliscrili r answer ER. in lclcphoius @'slcni, a calling line, a called iiuc, a cir uit l'or connecting the two. said circuit baring a manual section and all automatic section. the manual secs tiou comprising manual trunking (units meat, th automatic sucti n comprising an automatic iu'ogi'ussiu-ly movabletrunlting switch, a battery l'or supplviun' current to the said circuit, a busy test circuit tor the callcil line, means l'or applying a guarding i olclit'ial to said test ircuit u'lu'u a callcil lino l us'vt r lui c rl'jlidl l'or said umuual inual ionti l uu-aus oud r the coulr -l a" ad lc-d i-iri oil to l! rcrsithe but {cry supply to SLllIl manual M'fifillfll if 11m called line is busy, and means fut 0 10mm ing hillll, signal, respmisii'c in will lvvei's zil of current, said mean i'illklpl'ifiing a p013 izeil relay.

:29. In :1 te lvplmms hrm :i milling lillu, in-illenl line, :1 vim-nit 1 1:1 mluieulin the {W will min-Hit inning n mammal uiiim mail :in illli lllilllt, hLt'tll'l l, ilie izizixiuzil 00 ilflll (-mnprising mammal trunking equipment, tl'iv automatic sectiun minimising;

:m filliih mat ic plngressii'cly movable trunking switch, :L lmtfm'y for supplying current t0 t1)? said cirvuit', a busy test cii i-uii fur thi milled limg moans fm' applying :1 gum-ding: potrnliul in will Lust, viz-Quit when ii (-allml line is. luv a busy signal for said :immmi sm-t iun, In signal cunl'ml 11mins mulm' thu ('Hflllfll if? said rest Plifflllt [0 reverse the lizittm fmgr ply ln siiial manual imriimi if th s ('Zlll("(l line i inlay, 2110mm i'ur Uptfl'ill lllgf will signal, was; :msim u said I'BVPPSZLI if vim-exit. siziiil IIHJEUJS L'DHIPI'lSiDg a PUlIHiZQli relay, uwzum For zziitnlnntirally zlpplj 'ingr ringing i'ui'i'vni in H1? (illlPfl linu if it ir iillv tillll Fmizilvr' miijuntiy iiiic-i'r'uf itilip nw-iiil ringing; warren? :mil ilLPZHiH i-uiiiiwiwl in swies with a =ui1ym 0i ringing ('IUI'iHt fur ll (mm-vii V Lll} same {ruin llH' line is HIGH as trlmialied aub- Hl'iilwi' answers.

3U. Tn :2 ni-milmimtic trunking m :m wppmtnrs mm] and an iiiitiimaiia mi-utur swilvli fur cXlululing a irunnevtion 1m twvvn lwn line-s. :1 battery fur supplyingvurwill aw film vmiiwctiun. :i ignai fur Hlllll curd, zmil llllilllh in miil 1 li'ieitmwitch for W- v'kl'hlll fij liacli nml furtli Ilw currvnl', in Hilifl ('HIIIHWHHH liar flushing Hllll signal a number il' tiimu n inlliuxilu ilmt Hue (uille-il line is Him}.

iii. In 1 lulvplmuu system the ue'ililliiamthin with two ivii pllmw Maliuns and inmms ii lllliili ii if an uulr-nmiiu switch and a trunk line accessible therein for connecting hil ld mirimm few PUHYH'HlliUH, uf means at one Will u! Hziiil fi'imk liliv 'In' lvmlei'lng Ettiil li'iinl; liiic inlay, 11ml llltiillh zit llw utlwr r-ml ul mill iiliill-i iimfor i-nntwiliiig said bus) ing minim. im-iihe talking VflllilllLiUlS uf siiei 121ml: line.

f. ln :1 tvlvplwm- ,syslvm, :1 milk line ivi'miimiing in an npvxzilmk pusiiiwn. m1 lilillllltll ii HWlH'll fur svizing mill trunk lino, moans Fml'lfl'lilm'lllfl' sniil trunk lino may to mill six itili. Ililll operator rnntrolluii moans fur qnnlimlliug Hillll lm ying mvnm (\Vl'l llw lillliing ('HYHlilPl'lI-Z's (if said liinili llilz".

i gInml ll V m0 at liicugm (m'ik i'nimiy, Elilllflifi, llilH 11111 day (if Fif li'iliilw lf l l TALBOT (i. MARTIN.

wiiiwssvs V C. W. Bi'rLL, Bmmium I). alus. 

